Chemical compounds

ABSTRACT

Compounds containing the grouping X-CH2-CH2-Si * where X is a nucleofugal group, e.g. halogen, phosphate, or sulphonium or ammonium, are useful as plant growth regulating agents, particularly as yield stimulants for Hevea brasiliensis.

United States Patent Gregory Aug. 5, 1975 1 CHEMICAL COMPOUNDS [56]References Cited [75] Inventor: Maurice James Gregory, Welwyn UNITEDSTATES PATENTS Garden 'W England 3,345,393 10/1967 Simmler et al.260/448.8 R x [73] Assigneez The Na'ural Rubber Prnducersv 3,597,4638/1971 Peterson 260/4482 N Research Association, England 3,631,19412/1971 LeGrow 260/448.8 R X [22] Filed: May 1972 Primary Examiner-PaulF. Shaver 2 N 249 553 Attorney, Agent, or FirmWenderoth, Lind & Ponack[30] Foreign Application Priority Data ABSTRACT May 3, 1971 UnitedKingdom 12798/71 Compounds containing the grouping XCH CH- -Si E where Xis a nucleofugal group, e.g. halogen, 1 Cl 3 R; 260/ phosphate, orsulphonium or ammonium, are useful as 2; 71/79 plant growth regulatingagents, particularly as yield [51 Int. Cl. C07f 7/18; C07f 7/08; C07f7/10 stimulants for Hevea brasiliensis. [58] Field Of Search 260/448.8R, 448.2 N

3 Claims, No Drawings CHEMICAL COMPOUNDS This invention relates tochemical compounds useful as plant growth regulators, to plant growthregulating compositions containing them, and to processes or eg onederived from a pyridinium or ammonium group. a

While we do not wish to be bound by any theory of how our inventionworks, we believe that the silicon h d f regulating h growth f plants, 5compounds with which the invention is concerned act Th f l ff whi h canb hi 'edo l i by decomposing in the presence of water in the plant hcompounds f h invention to l ht are di tissues to provide ethylene, andthat it is this ethylene as they are with numerous other plant growthregulawhich is mainly responsible for exerting the growth tors, andinclude the accelerated ripening of fruits, the ulatihg effect wefurther believe that y Compound acceleration of abscission, the breakingof dormancy in Containing the g p g of formula I above is Capable buds,shoots, tubers, corms and rhizomes and other of ecomp sing in thePresence of Water t provi e plant growth regulation effects.Particularly notable in hy our experiments is the effect of applying theltwill be appreciated that the rate of decomposition pounds f hinvention to h b -k f h bb t of these silicon compounds is important asfar as their Hevea brasiliensis, which effect is to prolong the flow ofgrowth regulating properties are eoneemed- In y latex f h tree ontapping d h b increase h cases it is believed that the most effectivegrowth regui ld f bb f h tree lation is achieved by a controlled slowrelease of ethyl- A -di to h invention there i id d a ene in the planttissues, sometimes over a period of a 3 55 for regulating plant growthwhich process (:Qmmonth 01' more. The rate Of decomposition in water Ofprises applying t the lan n effec iv m u f a the silicon compounds withwhich this invention is con- 1 plant growth regulator comprising aompound corp cerned can be varied over a range an approprii i h he i lgrouping; ate selection of the group X and of the three groups (otherthan CH CH X) attached to the silicon atom. This phenomenon is readilyseen by reference to the X CH2 CH2 Si 4 (I) following data.

in which X is a nucleofugal group, for example, a halogen atom or thegroup,

Half lives of various silanes in 0.1M aqueous phosphate buffers at pH 7and 25. 8+ Compound Half-life /PO. P O gap}oroetgyltilirnethoxyiiarie egowmirlls. g R2 z-zhl i zminri ifi a zaiiiixi ilane i /aiiiuirs2-chloroethyltrimethylsilane l min. N+ RI R2 N+ ethyl methyl2-(trimethoxysilyl)-ethyl 14 hours A- A sulphonium iodide where M is ahydrogen or metal atom or ammonium radical; R is a substituted orunsubstituted hydrocar- It ill l b understood th hil h rate f d 0" gr pp Chain y c) C ntaining from 1 to 40 composition of the silanes inaqueous solution might be 13 Carbon atoms; R2 and R3 are defined aS(bl1tI10! expected to influence the rate at which ethylene is genessarilyidentical with) R; qbN is a nitrogen-containing erated in the planttissue, other influences also control substituted or unsubstitutedheterocyclic ring linked to this rate. Of equal or greater importance isthe diffusion carbon via the quaternary nitrogen atom; and A is an ofthe silanes from the formulation medium into the anion, e.g. chloride,bromide, or methylsulphate. Any aqueous portions f h plant Th i ld banion may be used which is not phytotoxic to the plant pected that asolution of an oil soluble/water insoluble being treated at the rate ofapplication of the comil li d to a plant i h under i bl dipounds of theinvention WhiCh iS p y to regulate tions liberate ethylene more slowlythan a less reactive the growth of the plant. water soluble silaneapplied similarly. This phenome- In heterolytic fragmentation of organiccompounds, non is readily seen by reference to the following experiwhichis by far the most common type of fragmentation ment in Solution. ngroup (thfl nuCleofugai g p) leaves Three Hevea brasiliensis seedlingswere treated with with the electron p y which it was Originally2-chloroethyltrimethoxysilane (2 pl) applied as-a neat tached to therest of the molecule, i.e. as a nucleofuge. li id Th i il dli were t t dith th This group thereby becomes more n gati y n same weight ofcompound applied asa 12% solution in charge unit and is Convert d nto anuclcofugfli gpetroleum jelly. The following average yields of rubberment. This is usually an anion, e.g. halide, sulphoriate, were obtained(yield of mg of dry rubber, expressed as phosphate or thiocyanate, butmay be a neutral group, a percentage of pretreatment yields inparentheses).

Time after treatment in days: 3 7 12' 16 24 30 34 42 Plants treated twith neat compound: 2.1 2.2 1.3 1.1 0.9 0.8 1.2 1.0

(230) (245) (122) (I00) (90) (134) l 12) Plants treated g with solution:2.2 2.3 2.3 3.0 2.2 2.3 L8 0.9

. 164) I (2l5) (1.60) (164) (l28) (65) The more prolonged response tothe silane in petroleum jelly can be seen from the above data.

The silicon compounds with which the invention is concerned may beregarded as having the formula:

where X has been defined above. B, Q and Z may be all the same ordifferent, and may be selected from the following groups by way ofexample:

i. halogen, e.g. chlorine or bromine,

ii. alkyl having from l to 18 carbon atoms, e.g.

methyl, ethyl, isopropyl, tert.-butyl, dodecyl,

iii. alkoxy having from 1 to 18 carbon atoms, e.g.

methoxy, ethoxy, isopropoxy, tert.-butoxy, dodecanoxy, 1

iv. aryl, e.g. phenyl, tolyl,

v. hydroxyl,

vi. thio or alkylthio,

vii. dialkylamino ix. -CH -CH -X,

x. substituted alkyl or alkoxy, e.g. acyloxy-, hydroxyorhalogen-substituted alkyl or alkoxy.

This list is not exhaustive, but includes those groups which are likelyto be of interest from a commercial standpoint. As stated above, thereis no practical restriction on the nature of the groups B, Q and Z.

All these silicon compounds are hydrolysed by water with the productionof ethylene. In many cases, however, the first thing that happens whenthe compounds are mixed with water is the replacement of the groups B, Qor Z with hydroxyl groups. This appears in general to be the case whenB, Q and Z are alkoxy, halogen, thiol, alkylthio, dialkylamino oracyloxy groups, but not when B, Q and Z are alkyl or siloxane groups.So, in many cases, the compound which is hydrolysed with the productionof ethylene is a Z-substituted-ethyl hydroxy silane.

The group X is a nucleofugal group, and may be selected from thefollowing groups:

i. halogen, e.g. chlorine, bromine or iodine,

ii. orthophosphate or a monoor di-orthophosphate ester, I

iii. disubstituted sulphonium salt, e.g. hexyl methyl sulphonium iodide,

iv. trisubstituted ammonium salt, e.g. trimethylammonium salt or anitrogen-containing substituted or unsubstituted heterocyclic ring, e.g.a pyridine, piperidine or pyrrolidinc salt.

It is surmised that the speed of, decomposition of the compounds offormula ll may vary as follows when X is changed, the groups B, Q and Zremaining constant:

OSi

These sequences can only provide, at best, a rough guide to the rate ofdecomposition of any particular compound.

' These silicon compounds vary in physical properties from volatileliquids to crystalline solids. Although the majority of compounds areoil soluble and substantially insoluble in water, water solublederivatives can be obtained when the group X is ionic in nature, or whenB, Q or Z contain hyrophilic groups. While water solutions orsuspensions are not normally suitable for the storage or transport ofthe silicon compounds, due to their susceptibility to decomposition, itmay be convenient to make up aqueous compositions for immediateapplication. Such aqueous compositions should preferably have a pH ofnot more than 5 in order to minimise the initial unwanted hydrolysisbefore the compound reaches the plants.

Certain of the silicon compounds falling within the scope of formula llare new compounds, and are included as such in the present invention.Thus, the invention provides, as new compounds, compounds containing thegrouping of formula I, where X is:

where M is a hydrogen or metal atom or ammonium radical;

R is a substituted or unsubstituted hydrocarbon group (open chain orcyclic) containing from 1 to 18 carbon atoms; R and R are defined as(but are not necessarily identical with) R; and N is anitrogen-containing substituted or unsubstituted heterocyclic ringlinked to carbon via the quaternary nitrogen atom.

These compounds may be made by standard methods. In general, theintroduction of the desired nucleofugal group X is effected quiteseparately from the introduction of the desired groups B, Q and Z. Thus,for example, 2-chloroethyl trichlorosilane may be reacted with up to 3moles of an alkanol so as to introduce up to 3 alkoxy groups attached tothe silicon atom. The resulting compound may then be reacted withfurther reagents to introduce the desired group X in place of the2-chlorine atom.

The invention also includes a composition for regulating plant growth,which composition comprises at least one compound containing thegrouping of formula l where X is a nucleofugal group, in a liquidsolvent or dispersion medium, a viscous oily or greasy medium, or apulverulent and/or granular solid carrier.

Such compositions may contain, if desired, a surface active agent.

The compositions based on solid carriers may be applied in the form ofpowder or granules. Suitable solid carriers include, for example,kaolin, talc, bentonite, calcium carbonate, gypsum, magnesia,vermiculite, Fullers earth and kieselguhr.

Compositions based on liquid carriers may contain water and/or organicliquids as the carrier medium, and the active ingredient may be in theform of a solution, dispersion or emulsion in the liquid carrier.

Surface active agents, if used, may be of the anionic, cationic ornon-ionic type. Suitable agents of the anionic type include, forexample, fatty acid salts, salts of aliphatic monoesters of sulphuricacid, e.g. sodium dodecyl sulphate, salts of sulphonated aromaticcompounds, e.g. sodium dodccylbenzene sulphonate, salts oflignosulphonic acid and salts of alkyl-naphthalene sulphonie acids, e.g.sodium butylnaphthalene sulphonate. Suitable agents of the cationic typeinclude, for example, quaternary ammonium compounds, e.g.cetyltrimethylammonium bromide, dodecyltrimethylammonium chloride.Suitable agents of the nonionic type include, for example, thecondensation prod ucts of ethylene oxide with fatty alcohols such asolcyl alcohol, cetyl alcohol and lauryl alcohol, or with alkylphenolssuch as nonylphenol and oetyl cresol. Also included are the partialesters derived from long chain fatty acids and hexitol anhydrides (e.g.sorbitol monolaurate) and the condensation products of such partialesters with ethylene oxide. However, it is not advisable to usenon-ionic surfactants containing free hydroxyl groups when the siliconcompounds contain groups (B, O and Z) attached to the silicon atom, suchas halogen atoms, which are liable to react chemically with hydroxylgroups.

Compositions which are to be used in the form of solutions, dispersionsor emulsions of the active ingredi' ent in a liquid carrier aregenerally supplied in the form of concentrates containing a highproportion of the active ingredient, the concentrate being diluted withwater or an organic liquid before use. It is generally convenient forsuch concentrates to contain between and 80% by weight of the activeingredient. The concentration of active ingredient in compositionsactually applied to the plants (or to the locus of the plants) may varywidely according to the purpose for which they are to be used, but willgenerally contain between 0.001 and 50% by weight of active ingredient.

The rate of application of the silicon compounds will depend on numerousfactors, e.g. the plant species to be treated and the particularcompound used, and the optimum rate of application may therefore varywidely according to circumstances, As a general guide, however, a rateof application of 0.1 pounds per acre to pounds per acre of the activeingredient is usually suitable when applied to standing vegetation.

As stated above, the compositions of this invention are particularlyadvantageous for the treatment of Hen-u In'uxilicns'is to stimulate theyield and prolong the flow of rubber latex therefrom. A convenienttechnique is to apply the composition to scraped bark just below thetapping cut.

When treating fully grown trees, it is preferred to apply from 50 mg to1,000 mg, e.g. from 100 mg to 500 mg. of the silicon compound per tree.The concentration of the compound in the carrier is not critical. It isgenerally convenient, from a practical viewpoint, to apply a few gramsof composition to each tree.

1 It will generally be found suitable to repeat application of thecompounds at from. 2 to 6 month intervals.

Advantage may be taken of the yield stimulant effect of those compounds,either by tapping the tree at the same intensity, so as to obtain anincreased yield of rubber latex, or by reducing the tapping intensity,and hence labour costs, without loss of yield.

A compound which has come into widespread use, as a stimulant of theyield of rubber latex from Hevea brasiliensis, is 2-chloroethylphosphonic acid sold under the Trade Mark Ethrel. The followingadvantages attach to some compounds according to the present inventionin comparison with Ethrel:

A. Results indicate that some compounds according to the presentinvention have a greater and longerlasting effect on latex yield thanEthrel;

B. The compounds of this invention are generally safe compared toEthrel, which is a strong acid and requires careful handling;

C. Lipophilic compounds of this invention are less likely to be washedoff the tree, e.g. by rain, than Ethrel, which is rather water-soluble;

D. The range of compounds of this invention have a wide spectrum ofwater solubility and of rate of hydrolysis, so that different compoundsmay be selected suitable for different applications.

The following Examples illustrate the invention. Examples l to 15 relateto the preparation of certain silicon compounds falling within the scopeof formula 11, generally starting from a 2-silylethanol or a2-sily1ethyl halide, both known classes of compounds. Examples 16 to 37illustrate the effect of Z-Substituted-ethyl silane compounds as plantgrowth regulators.

EXAMPLE 1 Preparation of 2-(trimethylsilyl)ethyl diethyl phosphate.

A solution of 2-(trimethy1sily1)ethanol (1.28 g, 0.01 mole), andpyridine (0.79 g, 0.010 mole) in carbon tetrachloride (10 ml) wasallowed to react with diethyl phosphorochloridate (0.0105 mole) at 0overnight. Pyridine hydrochloride was filtered off and the solvent wasremoved to yield the product as a viscous oil.

Other phosphate esters may be made using this procedure, starting fromother alkylor aryl-substituted silyl ethanols.

EXAMPLE 2 A. Preparation of 2-hexanethioethyltrimethoxysilane.

Azo-bis-(isobutyronitrile) (3.2 g) was added to a mixture ofvinylt'rimethoxysilane g) and hexane-lthiol (64 g). The mixture waswarmed to reflux for onehalf hour. Distillation of the mixture gave theproduct as a colourless oil (88 g) b.p. 149152/26 mm.

Other thiol compounds may be made similarly.

B. Preparation of Z-(trimethoxysilyl)ethylhexylmethyl sulphonium iodide.

A solution of Z-hexanethioethyltrimethoxysilane 10 g) and methyl iodide(14 g) in methanol (10 ml) was refluxed for 4 hours. Removal of themethanol by distillation left the product as a brown viscous oil.

EXAMPLE 3 Preparation of 2-(trimethylsily1)ethylpyridinium bromide.

A solution of 2-bromoethyltrimethylsilane g) was dissolved in pyridineg) and left to react for 2 weeks at room temperature. Removal of thepyridine by distillation at reduced pressure (1 mm Hg) left the productas a brown 011.

EXAMPLE 4 Preparation of Z-(trimethylsilyl)ethyltrimethyl ammoniumiodide.

2-(Trimethylsilyl)ethylamine was reacted with methyl iodide (3 moles) inthe presence of 2 moles of pyridine.

EXAMPLE 5 Preparation of methylethyl 2-(trimethoxysilyl)-ethylsulphonium iodide.

a. Preparation of ethyl 2-(trimethoxysilyl)-ethy1 sulphide A stirredmixture of vinyl trimethoxysilane (150 g) and ethanethiol (75 ml) wasirradiated at 0 with a 100 watt medium pressure mercury lamp for 2hours. The mixture was then distilled to give ethyl 2-trimethoxysilyl)-ethyl sulphide (192 g) b.p. 104111/22 mm. (Found: C.39.4:; H, 8.5%; S. 15.3%. C H SiO requires: C. 40.0%; H. 8.6%; S. 15.2%

b. Preparation of methylethyl 2-(trimethoxysilyl)ethyl sulphoniumiodide.

EXAMPLE 6 Preparation of diphenyl 2-(trimethylsilyl)-ethyl phosphate. Asolution of 2-(trimethylsilyl)ethanol (22 g) diphenylphosphorochloridate(44.5 g) and pyridine (13.2 g) in carbon tetrachloride (200 ml) was leftat room temperature for 2 /2 days. The solution was filtered and passedthrough an alumina column (200 g). eluting with a further 2 X 200 ml ofcarbon tetrachloride. Removal of the solvent from the eluate leftdiphenyl 2-(trimethylsily1)-ethyl phosphate (35.5 g) as a colourlessoil. (Found: C. 58.1%: H. 6.6%; P. 8.7%. C H' PO si requires: C 58.3%;H. 6.6%; P. 8.9%).

EXAMPLE 7 Preparation of Z-(trimethoxysilyl)-ethyl pyridinium chloride.

A mixture of pyridine (4.8 g) and 2-chloroethyl- LII trimethoxysilanc(5.65 g) was heated at reflux for 5 hours. Diethyl ether (20 ml) wasadded to the cooled mixture. and the deliquescent pyridinium saltcrystallised out. The NMR spectrum of the salt in D 0 showed eighteenprotons, five as a multiplet (3.1 to 2.0 5) four as a pair of multiplets(0.4 to 0.1 5, and 2.8 to -3.4 5) and nine as a singlet (1.3 5).Chemical shifts are related to internal water as a standard, and adownfield shift is taken as being positive. (Found: C1, 13.4% C,H,,.SiO;;NCl requires 13.5%).

EXAMPLE 8 Preparation of Z-(dimethoxyethylsilyl)-ethyl pyridiniumchloride.

A mixture of (2-chloroethyl)dimethoxyethylsilane (5.0 g) and pyridine(4.0 g) were heated at reflux for 4 hours. The product was washed withanhydrous ether (5 X 10 ml) and dried over P 0 under vacuum. The productwas a deliquescent solid (7.0 g) m.p. 6265. (C H NO SiCI requires: C113.6%. Found: C] 13.0%).

EXAMPLE 9 Preparation of 2-(trimethylsilyl)ethyl dihydrogen phosphatedi-eyclohexylammonium salt.

A solution in acetonitrile (30 ml) of crystalline phosphoric acid (2.0g) and triethylamine 4.0 g) was added dropwise over 4 hours to a mixtureof 2- (trimethylsilyl)-ethano1 (3.0 g) and trichloroacetonitrile (8.65g) at room temperature. The mixture was left overnight, diluted withacetone (200 ml) and cyclohexylamine (15 ml) was added. The precipitatewas collected and recrystallised from water and then ethanol 10%cyelohexylamine to give the eyclohexylammonium salt. (1.3 g) m.p.252255. (C H H SiO P requires: C, 51% H, 10.4%; N, 7.7%; and a C:N ratioof 7.3. Found: C. 47.6%; H. 10.6%; N. 6.5%: C:N ratio 7.3).

EXAMPLE 10 Preparation of di-n-butyl 2-( di-n-butylmethylsilyl )-ethy1phosphate.

Dibutylphosphorochloridate (3.74 g) was added to a solution ofZ-(di-n-butyl methylsilyl)-ethanol (3 g) and pyridine 1.04 g) in carbontetrachloride 10 ml). The mixture was left overnight. filtered. and thefiltrate passed through an alumina column (20 g). eluting with a further3 X 20 ml of carbon tetrachloride. Removal of the solvent under vacuumleft the phosphate as a colourless oil (2.7 g). (Found: C. 58.6%; H.11.3%; C,,,H ;,S,-O P requires: C. 58.0%; H. 11.0%.

EXAMPLE 1 1 Preparation of diethyl Z-(diphenyl methylsilyl)-ethylphosphate The reaction described in Example 10 was carried out using2-(diphenylmethylsilyl)-ethanol (2.25 g). diethylphosphorochloridatc1.35 g). and pyridine (0.6 g) in carbon tetrachloride (10 ml). Diethyl2-(diphenylmethylsilyl)-ethyl phosphate was obtained as a colourless oil1.35 g) (C H Si O P requires: C. 60.5%. H. 7.1%; I Found: C 63.4%: H.7.8%).

EXAMPLE 12 Preparation of 2-(dimethoxyphenylsilyl) ethyl hexyl methylsulphonium iodide.

A solution of 2-(dimethyoxyphenylsilyl)-ethyl hexyl sulphide (8 g) andmethyl'iodide (25 g) in methanol ml) was heated at reflux for 4 hours.The solvent was removed by distillation and the residual oil was washedwith petroleum ether (3 X ml). Residual solvent was removed under vacuum(().l mm Hg) to leave the sulphonium salt as a pale yellow hygroscopicoil (9.4 g). (Found: l 27.2%; equivalent weight by titration, 432. C HSi 0 5 l requires: 280%. Equivalent weight 454).

EXAMPLE 13 Preparation of 2-(n-butyldimethoxysilyl) ethyl ethyl methylsulphonium iodide A solution of 2-(n-butyldimethoxysilyl)-ethyl ethylsulphide (8 g) and methyl iodide g) in methanol l5 ml) was heated atreflux for 4 hours. The solvent and excess methyl iodide was removed bydistillation to leave a clear yellow oil. This was washed with ether (3X 25 ml). Residual solvent was removed to leave the sulphonic salt as ayellow hygroscopic oil (l 1.2 g).

Found: l 33.9%, equivalent weight by titration 381 C H SiO Sl requires:l 33.6%; equivalent weight 378).

EXAMPLE 14 Preparation of ethyl methyl Z-(dimethyl n-pentyloxysilyl)ethyl sulphonium methylsulphate EXAMPLE 15 Preparation of ethyl methyl2-(tricthylsilyl)-ethyl sulphonium iodide.

Ethyl Z-(triethylsilyl) ethyl sulphide (8 g) was reacted with methyliodide as described in Example 13. The product was a brown viscous oill0. 5 g). (Found:

1 36.4%, equivalent weight by titration: 352, C H- Si Sl requires: l36.871, equivalent weight, 346).

EXAMPLE l6 2-Chloroethyltrimethoxysilane (2 [1.1) was applied to each ofthe stems of three Heveu brusiliensis seedlings. Over a period of 2weeks the increase in yield of dried rubber from these seedlings was102% relative to the yield from the seedlings for the ten days prior totreatment.

EXAMPLE 17 A solution [7 mg) of 2-ehloroethyltrimethoxysilane inpetroleum jelly (l27( w/w) was applied to three H(\'('I hrusilimzsisseedlings. Over a period of two weeks. the increase in yield of driedrubber from these seedlings was 5271 relative to the yield from theseedlings for the ten days prior to treatment.

EXAMPLE 18 A cream composition was prepared. consisting of:-

-Continued 2-chIt roethyltrimethoxysilane 5% w/w Sorbitol 20% Arlacell07z Mineral oil 10% Water 55% Such cream compositions are described inPlant Protection Limited British Patent Application No. 48970/71.Arlacel is a Registered Trade Mark for sorbitan long chain fatty esters.

0.1 g Aliquots of the cream were spread on aluminium foil and applied tothe third internode of tomato plants at the 5-6 leaf stage. The degreeof epinasty was assessed after five days, when the mean angle, subtendedto the stem, of the leaves was found to be 1 l4, compared to 54 inuntreated plants.

EXAMPLE 19 Alternate leaf blades were removed from Coleus plants bearingfour pairs of fully expanded leaves, so that petiole stubs approximately1.5 cm long were left attached to the main stem. The plants were thensprayed to run-off with a solution of 2-chloroethyltrimethoxysilanecontaining 0.2 or 0.5% w/v of the silane. The solvent used was 20% v/vacetone in water, and also contained 0.1% v/v of a surface active agentsold under the name of Lissapol NX" (Lissapol is a Registered Trade Markfor a surface active agent comprising a condensate of ethylene oxidewith p-nonyl phenol). Five days after treatment the number of debladedpetioles which had fallen off the stems of treated and untreated plantswere counted, with the following results.

Plants treated with:- Percent petioles abscissed 0.2%Z-chloroethyltrimethoxysilane 0.5% 2-chloroethyltrimethoxysilane Solventonly (control) 7.5

EXAMPLE 20 A 0.5% w/v solution of 2-chloroethyltrimethoxysilane,prepared as in Example l9 was painted on to ripe fruits of calamondin(Cirrus mitis) plants. The solution was applied twice to each fruit,allowing an interval of approximately ten minutes between eachapplication. The pull force necessary to detach each was measured 7 daysafter treatment, with the following results:

A 13% w/v solution of 2-chloroethyltrimethoxysilane in .palm oil wasapplied to a 1 /2 inch wide strip of scraped bark just below the tappingcut of Hevea brasilienxis trees (Clone "Ijirumlji l). The trees weretapped on alternate days using a ha|f-spiral tapping cut. The yield ofdried rubber obtained over a seven-week period was measured. with theresults shown in Table l.

Table I Effect of 2-ehloroethyltrimethoxysilane on the yield of rubberfrom Hevea brasiliensis. Grams of dry rubber per tree per tapping andexpressed as percentage of control in parentheses Weeks 1 2 3 4 6 7 MeanTrees treated with l3% Z-chloroethyltrimethoxy-silane l l8.3 102 107 8699 72 85 95 (289) (252) (2H). (18?) (208) (99) H62) (190) Trees treatedva'th palm oil 4| 40 46 48 73 52 50 EXAMPLE 2! A 5% w/v solution of2-chloroethyltriisopropoxysilane, prepared in the solvent given inExample 19, was sprayed to run-off on to tomato plants which were at thesixth leaf stage. The degree of epinasty was assessed after five days;when the mean angle, subtended to the stem, of the leaves was found tobe 86 compared to 62 in untreated plants.

Example 23 A cream composition was prepared consisting of:-Z-chloroethyltriisopropoxysilane 5% w/w Sorhitol Arlacel l071 Mineraloil [0% Water 5571 Plants treated with:- Percent petioles ahscissed0.571 Z-chloroethyltriisopropoxysilane 63 Solvent only 7.5

EXAMPLE Table 2 The effect of 2-chloroethyltriisopropoxysilane on theyield of rubber from Hevea brasiliensis Grams of dried rubber per treeper tapping and expressed as a percentage of control in parentheses.

Weeks 1 2 3 4 5 6 7 Mean for 7 weeks Trees treated withZ-chloroethyltri- 83 76 83 73 88 93 7O 8 l isopropoxysilane (205) (I89)(I64) (I59) (I85) (I28) (134) (I62) Trees treated with palm oil 4] 5] 4648 73 52 0.1 g aliquots of the cream were spread on aluminium EXAMPLE 26for] and applied to the third mternode ot tomato plants A cmlm wmwsmmwas prepared WI at the 5-6 leaf stage. The degree of epmasty was as- 0consisting of sessed after five days, when the mean angle, subtended""lf fsfiig' l' /l to the stem. of the leaves was found to he 1 18 com-Arum] m; pared with 54 in untreated plants. Mimml Water 5592 EXAMPLE 24Alternate leaf blades were removed from Coleus plants hearing four pairsof fully expanded leaves. so that petiole stubs approximately l.5 cmlong were left attached to the main stem. The plants were then sprayedto run-off with a solution of Z-chloroethyL triisopropoxysilane.prepared as in Example 22. Five days after treatment the number ofdebladed petioles which had fallen off the stems of treated anduntreated plants were counted. with the following results.

EXAMPLE 27 A 45); solution of Z-chloroethyltri-ndodccanoxysilane in palmoil was applied to a We inch wide strip of scraped bark just below thetapping cut of Hcwu hI'tIA'i/lt'llXiS trees ((Iunv 'Ijl'rundii l). Thetrees were tapped on alternate days using a half spiral tapping cut. Theyield of dried rubber obtained over a 7 week period was measured. andthe results are given in Table 3.

Table 3 The effect of 2-chloroethyltri-ndodecanoxysilane on the yield ofrubber from Hevea brasiliensis Grams of dried rubber per tree pertapping and expressed as percentages of control in parentheses Weeks I 23 5 6 7 Trees treated with 2-chloroethyltri-n- 86 SI 9] 77 87 99. 74 85dodecanoxysilane (210) (2(ll) (180) (I67) (I83) (136) (14!) (I69) Treestreated with palm oil 4] 40 51 46 48 73 S2 50 EXAMPLE 28 to be 86. Thesame angle in untreated plants was 62. 25

EXAMPLE 29 A cream composition consisting of:

Ethyl methvl Z-(trimethoxvsil 'l)-ethvl sul honium iodide Sorhitol 20%Arlacel I07: Mineral oil l()'/( Water 5571 was prepared. 0.1 g of thecream was spread on aluminapplied as to 1% inch wide strip of scrapedbark just below the tapping cut of Heveu brasiliensis. (Clone Tji- 2Orandji l The trees were tapped on alternate days using a half-spiraltapping cut. Over the 2 weeks after treatment, the mean yield of driedrubber per tapping per tree was found to be 37.8 g, whereas only 28.3g/tapping/tree was obtained from similar untreated trees used ascontrols.

EXAMPLES 31 to 34 Solutions of the compounds given in Table 4 in palm.oil were applied to a l /2 inch wide strip of scraped bark 30 just belowthe tapping cut of Heveu brasiliensis trees (Clone Tjirandji l The treeswere tapped on alternate days using a half-spiral tapping cut. The yieldof dried rubber obtained over a 4-week period was measured, with theresults shown in Table 4.

Table 4 Efi'ect of various B-substituted ethyl silanes on rubber yieldsfrom Hevea brasiliensis Example 7? active ingredient Mean yield overNumber Compound in palm oil w/w four weeks a) 31 Poly(2-chloroethylmethoxy) siloxane 10 36.8 (174) 322-Chloroethyldimethoxysilyl acetate 15 41.0 (193) 33 (2-Chloroethyl)chlorodimethoxysilane' 13 35.5 (167) 342-Chloroethylmethyldimethoxysilane 12 36.6 (l73) Palm oil alone(control) l.2

a) Expressed as grams of dry rubber per tree per tapping and aspercentage of Control in parentheses.

ium foil and applied to the third intcrnode of tomato plants at the 5-6leaf stage. The degree of epinasty was assessed five days afterapplication. when the mean angle subtended to the stem of the leaves ofthe plant was found to be l2() compared to 62 in untreated plants.

EXAMPLES 35 to 37 Hevea brasiliensis trees were treated as in Examples3l to 34 with solutions of the compounds given in Table 5. in palm oil.Rubber yields are given for a two week period in Table 5.

Table 5 Effect of various B-substituted ethylsilanes on rubber yieldsfrom Hevea brasiliensis a) Expressed grams of dr rubber per tree pertapping and as percentage of control in parentheses.

I claim: 1. A compound which is hydrolyzable in the presence of water toproduce ethylene and having the formula:

(viii) ix. CH CH X x. substituted alkyl or alkoxy.

2 A compound as claimed in claim 1, wherein X is:

and each of B, Q and Z is an aliphatic hydrocarbon group or an alkoxygroup containing from l to 8 carbon atdms.

3. A compound according to claim 1 wherein B, Q

and Z are methoxy, and X is wherein A- is iodide, R, is methyl and R isZ-hexyl

1. A COMPOUND WHICH IS HYDROLYZABLE IN THE PRESENCE OF WATER TO PRODUCEETHYLENE AND HAVING THE FORMULA:
 2. A compound as claimed in claim 1,wherein X is:
 3. A compound according to claim 1 wherein B, Q and Z aremethoxy, and X is